1. Field of the Invention
The present invention relates to a steel-concrete railroad tie construction in which the rails are supported on ties in the form of blocks of reinforced concrete possibly connected in pairs of cross-ties including a metal truss having its ends sealed in said ties.
2. Description of the Prior Art
This type of tie is mainly used in non-ballasted rails, where the ties rest on plates of vibration deadening material, directly supported in concrete bearings, in which they are generally embedded. These rails appear particularly in rail transport systems in tunnels, where the absence of ballast enables considerable reduction in tunnel height.
However, despite the use of reinforced concrete for reducing the need for trussings, the reinforced concrete structure of the ties requires that they be given a certain dimensional mass in order to have the required solidity and rigidity. Consideration must be given to the great pressures concentrated on the center of the tie at the rail upright during the passing of trains, which tend to stress the concrete in repeated centrally-applied flexures, something which is not desirable for concrete blocks.
It follows that, in order to resist these flexures, the ties must necessarily be rather massive, especially in height, which runs counter to the desired goal of a rail assembly which is as low as possible.